DOOM editor

Part of the reason for DOOM 's popularity was the development of editors which allowed for modification and add-ons from the community of users.

Many level editors were and still are available for DOOM; one of the first, and for a long time, one of the most widely-used, was DEU, the Doom Editor Utility, initially programmed by Brendon Wyber and improved by Raphael Quinet, who forked off a version called NewDEU in spring 1994, which soon got remerged into DEU to combine Wyber's and Quinet's efforts. DEU has been ported to a number of operating systems, but lost significance over time; however, many of today's editors still have their roots in DEU and its editing paradigm, including DETH, DeePsea, Linux Doom Editor, and Yadex. Other level editors include WadAuthor and the relatively young Doom Builder (initially released in summer 2003), which, among other things, features a 3D editing mode.

A number of other, specialized editors also were created over time to modify graphics and sound lumps, most notably Wintex and XWE. Things, such as monsters and items, and weapon behavior can also be modified to some degree using executable patching utilities such as WhackEd and DeHackEd.